Urban or built environment

The green belt regeneration project along the Byzantine Walls of Thessaloniki aims to revitalize the neglected green spaces surrounding these historic fortifications, which span 4 kilometers and are recognized as a UNESCO World Heritage site for their remarkable Byzantine architecture. The walls are located in Thessaloniki’s densely populated Upper Town, a factor that contributed to their environmental degradation. As such, the project focuses on restoring the degraded space surrounding the walls, improving the urban microclimate, and strengthening urban resilience while maintaining the area’s traditional character. By integrating heritage conservation with sustainable green infrastructure, the initiative seeks to provide both environmental and social benefits to the local community. Proposed by the Municipality of Thessaloniki and approved by the Greek government as part of a program that focuses on Central Macedonia, the project envisions a revitalized green zone along the walls, with vegetation and different types of trees being planted. However, some local families have expressed concerns, as the project involved the demolition of certain homes in the officially designated green belt area. (Refs. 1, 2, 3, 4, 14).

The Jardim do Caracol da Penha project transformed a vacant urban area into a community garden and recreational space in Lisbon. Initially planned as a parking lot, the project was reimagined by local residents, led by Rita Vieira Cruz, and submitted to the Participatory Budget in 2016, garnering over 9,000 votes (Ref 2). The one-hectare garden connects the Arroios and Penha de França parishes and features leisure areas, an amphitheatre, playgrounds, and a community garden (Ref 4). Its design was shaped by citizen input, emphasizing sustainability and accessibility, with plans to support activities such as outdoor cinema and community gatherings (Ref 2).

The City of Marseille is engaged in a city-wide project to develop community gardens across its territory. It supports project leaders by providing municipal land and offering a framework along with technical support (Ref 5). Currently, there are 80 community gardens, including 66 shared gardens and 14 family gardens, covering nearly 32 hectares in total (Ref 1).
Marseille aims to provide all residents with spaces for relaxation and socialization in every neighbourhood, particularly fostering shared gardening spaces in neglected land, forgotten squares, building bases, or areas awaiting development. (Ref 1). Community gardens contribute to the city's beautification and support biodiversity (Ref 1) and are founded on values of solidarity, conviviality, and fostering connections between generations and cultures (Ref 4). This initiative also addresses the issue of agricultural land disappearing due to urbanization, while Marseille's many abandoned wastelands offer genuine opportunities to rethink production models (Ref 3).
The city has created a Charter to be signed between the city and garden managers, which can include groups of residents or associations (Ref 2). The charter includes criteria such as citizen involvement, fostering social connections, promoting biodiversity, restoring soils’ health, planting local species, and eco-responsible gardening practices (Ref 2). In return, the city supports the development of these gardens, providing land and offering technical and methodological assistance, including soil analysis and advice on environmentally friendly gardening practices (Ref 2). Additionally, community gardens can serve an economic purpose by creating jobs and enabling the production of healthy and flavorful fruits and vegetables at a lower cost (Ref 2).

Phoenix is America’s fifth largest and hottest city, a sprawling urban heat island which has expanded without adequate consideration to climate and environmental factors like water scarcity and extreme heat (1). ​Multiple heat records were broken in 2023 including 133 days over 100F (37.7C), and 55 days topping 110F (43C) (1). Only around 9% of Phoenix is protected by tree canopies, yet this citywide figure masks vast inequities between wealthy, majority-white neighborhoods (1). As a response, the City of Phoenix has adopted an equity-driven heat mitigation plan to create a shadier, more livable environment amid rising temperatures and hundreds of heat-related deaths (1). Part of this plan created the Community Canopy Grant program, which offers public schools, churches and homes in qualifying census tracts – low-income neighborhoods with little shade funds for tree planting projects (1). One neighborhood, Grant Park is one of the city’s oldest neighborhoods – and one of the most neglected (1). It is a red lined neighborhood with higher pollution levels, less vegetation, more noise pollution and higher temperatures (1). To change the inequity and create enough shade to provide residents and passersby reprieve from the heat, the city planted around 40 trees in the Grant Park neighborhood within household yards (1-2). Residents can choose from a list of 19 native and desert-adapted trees including the Texas olive, Chinese red pistache and Chilean mesquites (1). The trees, which are a couple of years old and pretty heavy, are planted by contracted arborists (1). Following the planting process, each household was provided with a tree kit – a hose, irrigation timer and instrument to measure the soil pH and moisture, as well as written care instructions (1). This is the fourth tree planting effort by this city and the hope with this initiative is that it lasts (1).

Two stages of a project called "Flowering roadsides" have been created along a bike road stretch measuring 6,5 km between the areas of Gunnilse and Bergum in the eastern part of the City of Gothenburg. The projects came to be through citizens' initiatives and are carried out in cooperation between the City of Gothenburg and two local NGOs: The Bergum-Gunnilse Development Association and the Gothenburg branch of the Swedish Society for Nature Conservation (Gunnilse-Bergum utveckling & Göteborgs naturskyddsförening). The first stage of the project was carried out in 2021 and focused on taking inventory of species and ecosystems along the stretch and suggesting management options to promote biodiversity. The second stage is carried out from 2022 to 2024 and focuses on implementing and evaluating alternative management options to today's conventional management. Mowing and scraping are carried out to disturb weeds and benefit meadow flowers. Sand has been placed to create a habitat for wild bees. Signs were put up along the stretch to inform the public of the initiative, and benches will be renovated to create opportunities for recreation. The project receives funding from the Swedish Environmental Protection Agency through their local nature conservation investment, LONA. The project falls under the umbrella project of "the world's longest meadow", organised nationally by the Swedish Society for Nature Conservation [Ref. 1, 3, 4]. The goal of that project is to transform 1000 km of Swedish roadsides into flowering meadows with high biodiversity richness [Ref. 2].

The greening of the Luceafarul theater esplanade is an initiative that is part of a corporate social responsibility strategy by the real estate company IULIUS (3, p. 86 & 89). The initiative aimed to expand and complement the green spaces and landscape design of the company's urban ensemble, Palas, located in the center of Iași (1 & 2). The space was previously occupied by a building owned by the company (5). Initially, the plan was to transform the building into a business center after donating it to the municipality (8). However, IULIUS and the Municipality of Iași agreed to demolish the structure and design a public space for the citizens instead (5 to 8). This decision was also influenced by the public’s desire to keep the area open, maintaining a clear view of the historical landscape, which was later incorporated into the municipality’s urban planning (8 & 9).
The design features a green field of 2,100 square meters, including 35 trees of various species (chestnuts, plane trees, and Ginkgo Biloba imported from nurseries in Italy) and 3,000 shrubs and bushes (1 & 2). The vegetation is maintained through an automated irrigation system (1 & 2).
The initiative aims to improve access to green spaces in Iași (3, p. 86) and to provide a space for recreation, relaxation, and leisure, with benches installed throughout the area (1 & 2). IULIUS intentionally places green space projects in central urban areas to ensure they are accessible to all residents (3, p. 86). Additionally, the municipality requested that the green space enhance the area's microclimate and improve the aesthetic appeal of the surrounding cultural landmarks (9, p. 6).

In response to rising food prices and knowing that much of the country's agriculture depends on imported chemical fertilisers, the Municipality of La Molina has developed the Molihuertos programme to provide the residents of the district of La Molina with organic crops for their own consumption and to improve their food security (1, 3). As part of the programme, the municipality implemented municipal plots in different parks in the district. Eleven plots were installed in O'Higgins Park, where residents actively participate in the planting and subsequent harvesting of vegetables, aromatic and medicinal plants, which they consume by themselves (2, 3). Through the programme, the municipality trains and provides different varieties of vegetables and aromatic herbs to more than 800 currently enrolled residents (2). These gardens are managed under organic agriculture, which would help to mitigate a possible overpricing and/or shortage of vegetables in Lima, as they do not depend on chemical fertilisers such as urea, but on organic fertilisers such as compost and manure (3). In addition, residents can sign up to receive drawers with planted vegetables so that they can plant and harvest them at home, either for self-sufficiency or to sell if they wish to do so in the itinerant markets organised by the municipality (9).

‘Grün macht Schule’ has been informing, advising, and supporting schools and school initiatives in Berlin since 1983 in the planning and realization of schoolyard projects. The program focuses on improving school playgrounds by creating child-friendly, natural habitats and ecological learning spaces, making schoolyards better equipped to address climate change. In 2012, the program expanded with the launch of the ‘Grün macht Schule - KinderGARTEN’ funding initiative, which extended support to kindergartens.
Over the past four decades, with the program’s assistance, Berlin has seen the transformation of large, unstructured schoolyards into smaller, creative playgrounds. These spaces now feature imaginative and artistic objects alongside facilities for play, exercise, and communication. Additionally, many school gardens and biotopes have been established or restored, turning school grounds into vibrant ecological and educational environments .
The projects are largely driven by schools’ self-initiatives, with ‘Grün macht Schule’ offering support throughout. This grassroots approach fosters pride and a sense of ownership among school communities, strengthening their identification with the results. The collaborative effort also enriches educational practices, promoting inclusion, integration, and democratic participation. Such initiatives offer a hands-on experience with sustainable climate protection projects, making these efforts tangible and impactful in everyday school life.
In addition to its project-based support, ‘Grün macht Schule’ provides training for school teams, organizes regional and national conferences, and hosts seminars and lectures to share best practices and inspire further action .
The program is a cooperative effort between the Senate Department for Education, Youth and Family and the association Freilandlabor Britz e.V., operating under the guidance of the Senate Department. (Ref. 1-4, 6)

As heat waves and high temperatures intensify due to climate change and urbanization, the City of Phoenix is exploring how to reintroduce tree shade into urban spaces to create a more equitable, livable environment. In 2014, the city set a goal to shade at least 25% of Phoenix by 2030, known as the Tree and Shade Master Plan. Achieving this ambitious target requires substantial resources and active community participation.
A key player in this initiative is Trees Matter, an environmental nonprofit dedicated to helping Phoenix reach its shade goals. Trees Matter not only works to expand and sustain the city’s tree canopy but also aims to foster environmental equity. Among its initiatives, the Trees for Schools program promotes tree planting in schools while educating staff and students about the significance of trees and tree care.
Silvestre Herrera Elementary School is one example where the Trees for Schools program has made a direct impact. As part of this program, 30 trees were planted on the school grounds, involving students, staff, and community volunteers in the process. These new trees offer critical environmental benefits, including shade, air purification, dust reduction, food production, and carbon sequestration. Additionally, tree presence has been linked to improved physical and mental health outcomes.
Beyond the immediate environmental gains, the project also offers educational value by involving students, staff, and maintenance crews in hands-on learning about tree care and environmental stewardship. This approach ensures that participants are equipped with the knowledge and skills needed to care for the trees long term, reinforcing both sustainability and community resilience.
Through these combined efforts, Phoenix is making strides toward a greener, more shaded future—one that benefits not only the environment but also the well-being and health of its residents. (1-5)

The Olaya Herrera neighbourhood in Cartagena has been the focus of a series of projects that involve ecological restoration, environmental education, and community resilience building. These initiatives have centred around the restoration of the Ciénaga de la Virgen, an ecologically significant but heavily degraded coastal wetland bordering the neighbourhood. The primary goals of the projects in Olaya Herrera include the restoration of degraded mangrove ecosystems, mitigation of flooding and water pollution, strengthening community participation in environmental management, and promoting sustainable urban environments (ref 1, 2). The project is led by the EPA Cartagena, which coordinates actions such as collecting solid waste, planting timber trees and ornamental plants, and restoring green spaces that had become informal dumping grounds (ref 1). It also includes a community-led initiative called Los Guardabosques de Olaya that focuses on reforestation and environmental stewardship, it involves children, youth, and local mothers in reforesting mangrove areas around the Ciénaga de la Virgen. The community has established a mangrove nursery and employs innovative waste management practices, such as installing traps in canals to prevent solid waste from entering the Ciénaga (ref 2). The project also involves the private sector in 2022, the EPA led a campaign with local companies like Konfirma, Acuacar, and Pacaribe that focused on improving environmental health through the removal of 10 cubic meters of waste, promoting healthy living environments and fostering community participation in environmental monitoring and waste management practices​ (ref 4). Also, in collaboration with community leaders and local companies, the ANDI-TRASO Alliance supports large-scale reforestation and restoration activities in the southern parts of the Ciénaga de la Virgen adjacent to Olaya Herrera. The alliance plans to plant 40,000 mangrove seedlings (ref 6).